Table 1.

Patient characteristics of children, young adults, and adults initiating SSRI treatment^a

	Children 5–17 yearsb (n=51,948)		Young adults 18–24 years (n=51,653)		Adults 25–64 years (n=395,550)
Patient characteristics	No.	%	No.	%	No.	%
Time period of treatment initiation
Period 1: January 1, 2000 to June 18, 2003c	9,829	19	8,531	17	72,426	18
Period 2: June 19, 2003 to October 14, 2004	4,826	9	4,248	8	34,996	9
Period 3: October 15, 2004 to May 1, 2007	14,719	28	15,145	29	109,814	28
Period 4: May, 2, 2007 to Dec. 31, 2009	22,574	43	23,729	46	178,314	45
Female	28,913	56	34,753	67	268,820	68
SSRI agent
Citalopram	8,042	15	12,579	24	98,296	25
Fluoxetine	18,358	35	12,867	25	88,045	22
Paroxetine	5,929	11	8,678	17	77,071	19
Sertraline	19,619	38	17,529	34	132,138	33
Provider specialty
Psychiatry	10,876	21	5,240	10	20,848	5
Psychology	3,046	6	1,485	3	7,827	2
General practice	17,855	34	18,871	37	113,066	29
Other	12,095	23	15,487	30	144,792	37
Unknown	8,076	16	10,570	20	109,017	28
Depression severity
Primary inpatient diagnosis ≤30 days pre-initiation	1,366	3	572	1	1,075	0
Primary inpatient diagnosis 31–360 days pre-initiation	243	0	139	0	287	0
Non-primary inpatient diagnosis	675	1	505	1	3,198	1
≥2 outpatient diagnoses	14,846	29	12,415	24	66,567	17
1 outpatient diagnosis	7,912	15	9,821	19	60,610	15
No depression diagnosis	25,906	50	28,201	55	263,813	67
Suicide attempt	458	1	303	1	355	0
Bipolar disorder	1,454	3	1,109	2	4,121	1
ADHD	11,186	22	2,958	6	3,611	1
Anxiety	15,012	29	14,659	28	87,061	22
Substance use disorder	1,957	4	4,072	8	26,135	7
Psychiatric hospitalization, prior year (1+)	1,791	3	842	2	1,826	0
Non-psychiatric hospitalization, prior year (1+)	2,066	4	4,299	8	44,121	11
Outpatient visits, prior year
< 5	12,914	25	15,143	29	94,496	24
5 – 9	14,313	28	14,520	28	95,330	24
10 – 19	15,178	29	13,843	27	110,316	28
≥ 20	9,543	18	8,147	16	95,408	24
Generic prescription drug count, prior year
None	8,567	17	6,538	13	34,818	9
1 – 2	17,534	34	14,151	27	87,098	22
3 – 4	11,882	23	11,706	23	80,517	20
≥ 5	13,965	27	19,258	37	119,960	30
High-potency prescription opiate usage	163	0	488	1	6,789	2
Mid-potency prescription opiate usage	6,230	12	13,814	27	119,960	30
Cancer	288	1	321	1	17,208	4
Cardiac arrhythmia	866	2	1,027	2	16,169	4
Diabetes	462	1	681	1	32,116	8
Cerebrovascular disease	109	0	169	0	8,564	2
Cluster headaches/migraines	1,566	3	2,099	4	16,088	4
Seizures	572	1	379	1	2,421	1

^aPatient characteristics collected in the year prior to SSRI initiation. Healthcare utilization measures included the number of outpatient visits, hospitalizations, and prescription medications in the prior year. Prior suicide attempt was defined with external cause of injury codes (E950.x–E959.x) and mid- and high-potency opiate prescriptions were defined based on National Drug Code. Psychiatric and non-psychiatric morbidities that were prevalent in all age groups were used to help describe the health status of the study cohort and were defined with ICD-9-CM codes: bipolar disorder (296.4–296.9), ADHD (314.x), anxiety disorder (300.0, 300.2, 300.3), substance use disorder (291.x, 292.x, 303.x–305.x), cancer (140.x–209.x), cardiac arrhythmia (427.x), diabetes (250.x), cerebrovascular disease (430.x–438.x), cluster headaches/migraines (346.x), and seizures (345.x). The hierarchical measure of depression severity included 5 levels for patients with at least 1 depression diagnosis: a primary (first listed) inpatient depression diagnosis ≤30 days prior to SSRI initiation (most severe) or 31–360 days, a non-primary inpatient depression diagnosis, 2+ outpatient depression diagnoses in the year prior to SSRI initiation, and 1 outpatient depression diagnosis (least severe).

^b5–9 years (n=6,776), 10–12 years (n=9,175), 13–17 years (n=35,997)

^cPeriod 1a: 5–17 years (n=4,678), 18–24 years (n=4,223), 25–64 years (n=35,727)